The oxygen abundance appears to vary within streamers, being lower
in the core than in the leg of streamers.  Here we show the behavior
of the oxygen abundance vs. height along radii which intersect
different sections of a streamer observed by UVCS on July 6, 1996.
The top panel gives: a semi-circle (red), outlining the limb of the
Sun; a set of radials (dashed lines, black), 10 degrees apart, on the
eastern side of the Sun; sections of circles whose radii are,
respectively, 2, 3, 4 solar radii (dashed lines, red); isophotes
(blue, solid line) of the O VI 1032 line intensity
(log I = 9 erg cm^-2 s^-1 sr^-1 for the first isophote,
log I = 6.9 erg cm^-2 s^-1 sr^-1 for the last isophote)
showing the streamer configuration; several symbols giving the
location, within the streamer body, where the oxygen abundance has
been evaluated.  The bottom panel gives the oxygen abundance at
several positions, within the streamer: the oxygen abundance is
higher at the streamer edge and tends to decrease with altitude.
This result is obtained from UVCS measurements of the O VI 1032 and
1037 line widths and intensities and from densities derived from
LASCO C2 data, assuming an electron temperature, constant across
the streamer, which decreases with altitude (Zangrilli et al., 2001,
submitted to the Proceedings of the Joint SOHO-ACE Workshop, Bern,
March 6-9, 2001).